1. Field of The Invention
The present invention relates generally to a power supply circuit for headlamp assemblies which are mounted on automatic vehicles and each of which has high-beam and low-beam valves for high-beam and low-beam lighting, respectively. More specifically, the invention relates to an improved power supply circuit in which the high-beam and low-beam valves can be selectively connected to a power source.
2. Description of The Background Art
Some of such power supply circuits are provided with a combination switch which has a plurality of terminals. Each of the terminals is electrically connected to one of the low-beam or high-beam valves of headlamp assemblies or to a power source. The combination switch has three positions such as OFF, first and second positions, each of which has three modes such as low-beam, high-beam and flashing modes. In accordance with the selection of the position and mode, either the low-beam valves or high-beam valves of headlamp assemblies are in communication with the power supply via two connected terminals to be turned on, and the other valves are not turned on. According to such power supply circuits, only the high-beam valves can be turned on when in the high beam mode. Therefore, the illuminance of headlamp is not sufficient during the high beam mode.